MARO
MARO's whole pitch is the waistband. The industry-standard trick is to label a pair "100% cotton (exclusive of trim)" while the covered waistband is spandex and polyester riding against the skin all day. MARO instead knits its band from organic cotton and natural rubber, so the pair is plastic-free end to end - the men's analog to the natural-rubber-band approach The Very Good Bra uses in women's underwear. Natural rubber is a latex, which is the one caveat.
How clear are their specs?
States the body is 100% GOTS organic cotton and the waistband is 60% organic cotton / 40% natural rubber, covered in organic cotton, with OEKO-TEX dyes.